\documentclass{article}
\usepackage{graphicx}
\usepackage{array}
\usepackage{booktabs}

\begin{document}
\begin{tabular}{@{}lllllll@{}}
  \toprule
  &  & \multicolumn{5}{c@{}}{Average MuchLonger Name Goes Here:}  \\
  \cmidrule(){3-7}
   a & \rotatebox{90}{\parbox{2cm}{Was this\\ Identified by You?}}& C & D & E & F & G\\ 
  \midrule
   5\% & 12.9\% & 7.3281 & 7.2445 & 2.1601 & 4.3438 & 4.2821 \\ 
     &   & (.4038) & (.5058) & (.9049) & (.9032) & (.8831) \\ 
  \bottomrule
\end{tabular}
\end{document}
